52 l)r Davy's Observations on Phosphorus. 



from the blacksmith's shop) has had a similar extinguishing ef- 

 fect, though in a less degree. One volume of it, mixed with 

 fifty-nine of common air, has prevented phosphorus immersed 

 from shining ; diluted more than this, it lost its preventive 

 power. This result is probably owing either to the presence of 

 a little vapour somewhat analogous to that of naphtha, on which 

 the odour of hydrogen gas thus procured depends (and the 

 odour of this gas was strong) ; or, on the presence of a little car- 

 buretted hydrogen formed by the union of the nascent hydrogen 

 and the carbon of the cast-iron or steel at the instant of separa- 

 tion. The result of the analysis of the gas by the explosion 

 with oxygen by means of the electric spark, has been rather 

 favourable to the first supposition ; but the quantity of carbonic 

 acid gas formed was so extremely small, that it was impossible to 

 decide positively. The fact that hydrogen gas procured by 

 means of very pure steel, such as piano-forte wire, does not, when 

 mixed with atmospheiic air, extinguish the light of phosphorus, 

 is favourable to the same conclusion. 



Some of the results described are not without interest in rela- 

 tion to practical chemistry. Mr Graham has pointed out the 

 applicability of phosphorus to detect in mixed gases the pre- 

 sence of very minute quantities of carburetted hydrogen. It is 

 equally applicable as a test of the purity of muriatic acid gas and 

 carbonic acid, and hydrogen gas. If they contain the slightest 

 trace of common air, phosphorus will shine in these gases, pro- 

 vided they are otherwise unadulterated. It has been shewn 

 how it is capable of detecting an adulteration of hydrogen, which 

 had hitherto, I believe, escaped detection ; and, it may also be 

 employed to detect similar impurities in other gases, in which, 

 with an admixture of common air, phosphorus usually shines. 

 I need not point out the caution that is required in deciding on 

 the absence of oxygen, in any mixed gas in which phosphorus 

 does not become luminous. 



In relation to the results in general, they are not without some 

 interest theoretically considered, as belonging to the more obscure 

 phenomena of chemistry, somewhat analogous to what we wit- 

 ness in the animal and vegetable kingdoms, in which notable 

 changes during life and after death are taking place, owing to 

 the action of causes which we are not able to appreciate, or per- 

 haps of substances which have hit^ierto eluded detection, 

 Malta, March 1833. 



